10. Digital imaging part 3

Question 1

What does Doubling/halving exposure do to the S# with Fuji?

Answer 1

Cuts the S# in half/double

Question 2

If the S# is over 1000, what does that mean?

Answer 2

Severely underexposed (repeat)

Question 3

If the S# is less than 50, what does that mean?

Answer 3

Overexposed (can be a repeat)

Question 4

What is the optimal exposure range for Carestream (CR, DDR)?

Answer 4

EI:(1800-2200)

Question 5

What does Doubling/halving exposure changes do the EI value using Carestream?

Answer 5

Doubling/halving exposure changes EI by 300

Question 6

What is the relationship between EI value and exposure values with carestream?

Answer 6

Directly proportional to exposure

Question 7

What does it mean if the EI value is less than 1250 with Carestream?

Answer 7

Severely underexposed (repeat)

Question 8

What does it mean if the EI value is greater than 2750 with Carestream?

Answer 8

Overexposed (may need to be repeat)

Question 9

How does Agfa measure EI values?

Answer 9

Log Median Value (LgM)

Question 10

What is the optimal EI range for Agfa?

Answer 10

(1.95-2.6)

Question 11

What is the relationship between Log Median Value (LgM)
and exposure values?

Answer 11

Direct relationship

Question 12

What does Doubling/halving exposure to the the LgM

Answer 12

Doubling/halving exposure changes LgM by 0.3

Question 13

What is the relationship between the DI value and exposure?

Answer 13

• Directly proportional to exposure but not linear
• As you increase one step in mA, will increase DI value by one step

Question 14

What is the Optimal DI Range (green)?

Answer 14

-3.0 to 2.0

Question 15

What is the acceptable DI range (yellow)?

negative and positive

Answer 15

-3.0 to -5.0 and 2.0 to 4.0

Question 16

What is out of the acceptable DI range (orange)

Answer 16

< -5 or >4

Question 17

What is the reason that we don’t use the highest kVp and lowest mAs?

Answer 17

Because there would not be any photons to actually penetrate the IR

Question 18

What happens if you under/over expose using DDR?

Answer 18

Automatic Rescaling: Puts contrast values into an acceptable range